This invention relates to contact devices for use in the testing of printed circuits.
Machines used in the electronic industry for testing printed circuits generally comprise a plate through which extend apertures in well defined positions. These apertures are intended to accommodate contact devices for carrying out electrical measurements at particular points of a printed circuit card positioned parallel to the plate.
To this end, the contact devices used so far each comprise a seating member intended to be permanently mounted in one of the apertures of the plate, which seating member serves firstly mechanically to hold in position the contact head to the side of the plate intended to face the printed circuit card, and secondly electrically to connect the contact head with the testing system as such.
The seating member is generally formed by a receptacle in which is removably mounted an interchangeable assembly or unit comprising of a guide tube, a coiled compression spring housed in the tube and a contact head projecting from one end of the tube and adapted axially to slide in the tube against the action of the spring.
The operative portion of the contact head varies considerably in shape depending on the nature of the printed circuit areas where measurements are to be made.
Interchangeable assemblies or units are awkward to manufacture and assemble because of the simultaneous inclusion of the guide tube, of the compression spring and of the contact head. It is therefore not rational to use such assemblies.